1. Field of the Disclosure
This disclosure relates to an organic light emitting diode display (OLED) device, and more particularly to an OLED device of the top-emission inverted type adapted to reduce the process of forming a thin film transistor on a metal substrate, and a manufacturing method thereof.
2. Description of the Related Art
OLED devices of a self luminous type can be light and slim since they do not need the backlight units required for liquid crystal display devices. Also, the OLED devices can be manufactured through a simple process. Moreover, the OLED devices have a low voltage drive, a high luminous efficiency, and a wide viewing angle. In view of these points, the OLED devices have received a growing amount of attention as one of next-generation display devices.
The OLED devices each include thin film transistors arranged on a substrate, organic light emitting diodes connected to the respective thin film transistors, and a seal substrate covering the organic light emitting diodes. The organic light emitting diodes are configured to emit light. Such OLED devices can be classified into a bottom emission type and a top emission type according to light emitting directions.
The top emission OLED device is configured to emit light through a seal substrate. As such, the top emission OLED device has a larger aperture ratio than that of the bottom emission OLED device. Moreover, the top emission OLED device can be designed in a variety of formations because the aperture ratio is not subject to a driving element.
However, the top emission OLED device employs a process of forming a thin film transistor using a maximum of 11 masks. In other words, the formation process of a thin film transistor is very complex. As such, the manufacturing efficiency of the top emission OLED device is deteriorated and manufacturing costs of the top emission OLED device increases.
Moreover, the top emission OLED device includes cathode electrodes formed by patterning a corrodible conductive material in pixels, and an organic light emission layer and anodes sequentially formed on the cathode electrodes. As such, the cathode electrodes are very easily corroded. Such corrosion of the cathode electrodes deteriorates the reliability of the top emission OLED device.